Hospitalized

Lady Gaga had to get emergency care in Colorado due to the altitude, but she was well enough to take a selfie while she wore an oxygen mask.

In the photo, her big brown eyes shine as she wears the device over most of her face. "Altitude Sickness is no Joke! #hitThatHospitals--t #artRaveDenver many true ravers crowd tonight," she wrote along with the snap on Instagram.